1.3.3 Networks

Question 1

What is a network?

Answer 1

Two or more computers connected together that can transmit data

Question 2

What is a physical topology?

Answer 2

The physical layout of a network

Question 3

What is a logical topology?

Answer 3

The way in which data flows around a network

Question 4

What is a bus topology?

Answer 4

Network topology where all terminals are connected to a backbone cable

Question 5

What is the advantage of a bus topology?

Answer 5

Cheaper to set up as no additional hardware

Question 6

What are the two disadvantages of a bus topology?

Answer 6

If backbone cable fails, entire network disconnected
As traffic increases, performance decreases

Question 7

What is a star topology?

Answer 7

Uses a central node to direct the flow of data

Question 8

What can be used as a central node in a star topology?

Answer 8

A switch
A computer

Question 9

What are used to identify devices on a star topology?

Answer 9

MAC addresses

Question 10

What are the five advantages of a star topology?

Answer 10

Perfomance is consistent
If one cable fails, only that node is affected
Transmits data faster
Easy to add new nodes
No data collisons

Question 11

What are the two disadvantages of a star topology?

Answer 11

Expensive
If central switch fails, network fails

Question 12

What is a mesh topology?

Answer 12

Every node is connected to every other node

Question 13

What are the three advantages of a mesh topology?

Answer 13

No cabling cost
As nodes increase, reliabiity and speed of network increases
Faster due to no central switch

Question 14

What is the disadvantage of a mesh topology?

Answer 14

Difficult to maintain

Question 15

What are protocols?

Answer 15

Set of rules defining how two devices communicate with each other

Question 16

What is the Internet?

Answer 16

A network of networks
Allows computers across the world to communicate

Question 17

What is the TCP/IP stack?

Answer 17

A stack of networking protocols that work together to pass packets during communication

Question 18

Name the four layers of the TCP/IP stack.

Answer 18

Application
Transport
Network
Link

Question 19

What happens at the application layer?

Answer 19

Specifies what protocol needs to be used for the application being sent

Question 20

What happens at the transport layer?

Answer 20

End-to-end connection established between source and destination
Splits & labels data into packets
Requests retransmission of any lost packets

Question 21

What happens at the network layer?

Answer 21

Adds source and destination IP addresses
Routers use IP addresses to forward packets

Question 22

What happens at the link layer?

Answer 22

The connection between the network devices
Adds the MAC address identifying the NIC of source and destination computer

Question 23

Describe the layers of the TCP/IP stack on the recipient computer.

Answer 23

Link: Removes MAC addresses
Network: Removes IP addresses
Transport: Removes port number and reassembles packets
Application: Present data in form it was sent

Question 24

What is a LAN?

Answer 24

A network spread over a small geographical area typically located on a single site
Hardware usually owned and controlled by the organisation using it

Question 25

What is a WAN?

Answer 25

A network that covers a large geographical area Infrastructure leased from telecommunication companies who own and manage it

Question 26

What is a Domain Name System?

Answer 26

Method of naming internet resources Hierarchy where each smaller domain is seperated from larger by a full stop

Question 27

What is the purpose of a DNS server?

Answer 27

Translate domain names into IP addresses when accessing a website

Question 28

What is circuit switching?

Answer 28

A method of communication where a direct link is created between two devices and maintained for entire conversation

Question 29

What is the advantage of circuit switching?

Answer 29

Quicker reconstruction as data arrives in logical order

Question 30

What are the two disadvantages of circuit switching?

Answer 30

Devices must transfer and recieve data at the same rate Electrical interference from switches can corrupt or lose data

Question 31

What is packet switching?

Answer 31

A method of communicating packets of data across a network

Question 32

What are the three advantages of packet switching?

Answer 32

Methods to ensure data arrives Multiple routes if one breaks Can transfer packets over very large networks

Question 33

What is the disadvantage of packet switching?

Answer 33

Time is spent deconstructing and reconstructing data packets

Question 34

How are data packets split?

Answer 34

Header Payload Trailer

Question 35

What is included in the header of a packet?

Answer 35

Sender & recipient IP addresses Protocol being used Order of packets Time to live / hop limit

Question 36

What is included in the payload of a packet?

Answer 36

The raw data

Question 37

What is included in the trailer of a packet?

Answer 37

Checksum / cyclic redundancy check

Question 38

What is the hop limit of a data packet?

Answer 38

Set by the source of the packet Decremented by one each router (hop)

Question 39

Why is a hop limit needed?

Answer 39

To prevent data packets from circulating indefinitely with a network

Question 40

What is the checksum of a packet?

Answer 40

Value computed from a data packet to check whether data is received error free or not

Question 41

What is a firewall?

Answer 41

Device designed to prevent unauthorised access to a network

Question 42

Describe how a firewall works.

Answer 42

Two NICs between user and internet connection Pass packets between two NICS and compares them against packet filters Perform packet filtering

Question 43

What are packet filters?

Answer 43

A set of rules set by the firewall software

Question 44

What are proxy servers?

Answer 44

Intermediate that collects and sends data on behalf of user

Question 45

Give 3 features of proxy servers.

Answer 45

Protect privacy of usr who remains anonymous Cache frequently used website data so faster to load Reduce web traffic

Question 46

Give a use of proxy servers.

Answer 46

By administrators to prevent access to sensitive or irrevelant information at work/school

Question 47

What is a Network Interface Cards?

Answer 47

Required to connect a network Assign a MAC address to each device

Question 48

What is a switch?

Answer 48

Used to direct the flow of data across network Used in star topology

Question 49

What is a Wireless Access Point?

Answer 49

Allows devices to connect to a network wirelessly More commonly used to connect devices to a router Used in mesh networks

Question 50

What is a router?

Answer 50

Used to connect two or more networks Includes ISPs network to allow Internet connection

Question 51

What is a gateway?

Answer 51

Translates protocols so that both networks have same protocols Removes the header from packets before the remaining data is added with the new protocol of the new network

Question 52

What is a client-server network?

Answer 52

Terminals conncted to a server

Question 53

What is a client?

Answer 53

A terminal

Question 54

What is a server?

Answer 54

Powerful central computer Holds all important information and has extra processing power the clients can request to use

Question 55

What are the three advantages of a client-server network?

Answer 55

More secure Central backups Sharing data and resources

Question 56

What are the three disadvantages of a client-server network?

Answer 56

Expensive set up Trained staff are required to maintain server Single point of failure

Question 57

What is a peer-to-peer network?

Answer 57

Computers are all connected

Question 58

What are the three advantages of a peer-to-peer network?

Answer 58

Inexpensive set up Allows users to share resources Easy maintenance

Question 59

What are the two disadvantages of a peer-to-peer network?

Answer 59

Less secure No central backup